Bioinspired Fast Room-Temperature Self-Healing, Robust, Adhesive, and AIE Fluorescent Waterborne Polyurethane via Hierarchical Hydrogen Bonds and Use as a Strain Sensor

Developing a new generation of ecofriendly water-basedpolymericmaterials that integrate mechanical robustness, fast room-temperatureself-healing, adhesive, and fluorescence remains a formidable challenge.Herein, inspired by titin protein, a series of novel waterborne polyurethanes(WPU-CHZ-NAGA) containing irregular 6-fold and diamide hydrogen bondsare synthesized by introducing carbohydrazide (CHZ) and N,N-bis(2-hydroxyethyl)-3-amino propionyl glycinamide(HO-NAGA-OH) groups. The representative WPU-CHZ(2)-NAGA(3) exhibits outstanding mechanical properties (tensile strengthof 36.58 MPa, tearing energy of 81.2 kJ m(-2), andtoughness of 125.82 MJ m(-3)) and fast room-temperatureself-healing ability with the aid of ethanol (& GE;90% within 8h) originated from hierarchical hydrogen bonds. These properties aresuperior to those of most of the reported room-temperature self-healingpolymer materials. Benefiting from plentiful hydrogen bonds, the WPUmatrix achieves excellent adhesive properties without heating or addingcuring agents. Interestingly, WPU-CHZ(2)-NAGA(3) film emits inherent blue fluorescence due to the aggregation-inducedemission effect of tertiary amine groups, and its potential applicationsin information encryption and anticounterfeiting are further demonstrated.Specially, a eutectic gel strain sensor is also fabricated with WPU-CHZ(2)-NAGA(3) and deep eutectic solvent by a simple physicalblending method, which can be used to monitor the movement of humanfingers and wrists as well as the change in body temperature. In summary,this work provides new insight into the design and synthesis of multifunctionalWPU with fast room-temperature self-healing and high mechanical properties.